TORNADOES. 161 



made upon the same storm, that cyclones in the 

 northern hemisphere invariably sweep round the on- 

 ward travelling vortex of disturbance in one direction, 

 and southern cyclones in the contrary direction. If 

 we place a watch, face upwards, upon one of the 

 northern cyclone regions in a Mercator's chart, then 

 the motion of the hands is contrary to the direction in 

 which the cyclone whirls ; when the watch is shifted 

 to a southern cyclone region, the motion of the hands 

 takes place in the same direction as the cyclone 

 motion. This peculiarity is converted into the follow- 

 ing rule-of-thumb for sailors who encounter a cyclone, 

 and seek to escape from the region of fiercest storm :- 

 Facing the wind, the centre or vortex of the storm lies 

 to the right in the northern, to the left in the southern, 

 hemisphere. Safety lies in flying from the centre in 

 every case save one that is, when the sailor lies in 

 the direct track of the advancing vortex. In this 

 case, to fly from the centre would be to keep in the 

 storm-track ; the proper course for the sailor when 

 thus situated is to steer for the calmer side of the 

 storm-track. This is always the outside of the cj, as 

 will appear from a moment's consideration of the spiral 

 curve. traced out by a cyclone. Thus, if the seaman 

 scud before the wind in all other cases a dangerous 

 expedient in a cyclone* he will probably escape un- 

 scathed. There is, however, this danger, that the 



* A ship by scudding before the gale may if the captain is not 

 familiar with the laws of cyclones go round and round without 

 escaping. The ship 'Charles Heddle ' did this in the East Indies, 

 going round no less than five times. 



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